General Guide to Bonsai Care
Since bonsai plants are generally grown in containers, they will need regular watering to keep them healthy. The actual amount of water and frequency of water will depend on the location of the bonsai (i.e. shady location versus sunny location), the size of the bonsai, and the time of year. When watering, it is good to take into account the type of water you are using. If your water supply is heavily chlorinated, it is recommended to fill a container with water & let it sit for 24 hours before using it. This allows the chlorine to evaporate. Also, softened water is not good for your plants because it has too much salt for your plant's health. Use water from an outside tap which is not softened.
Thorough watering is recommended every one to three days in the spring, summer and fall; less in the winter. Do not let the roots dry out completely. If it is very hot and/or windy, watering more than once a day may be necessary. It is best to water in the early morning or late afternoon. The method of watering should simulate natural rainfall - use an attachment on the watering can or hose which makes the spray soft enough so as not to disturb the soil. Water until excess water runs out of drainage holes in the bottom of the pot. In particularly hot, dry weather, or if you are not sure you are watering thoroughly enough, the pot can be placed in a shallow pan of cool standing water (to 1" deep) and soaked for up to 1/2 hour. Notice how heavy the plant is when it is thoroughly watered. The difference in weight between wet and dry will help you to know when the roots are dry, even if the top of the soil is moist.
Use fertilizer in moderation. A liquid fertilizer like Master Nursery Liquid Gold or Fish Emulsion can be applied once a month in the main growing season. It is best to use the fertilizer at half the recommended amount to prevent burning. For flowering and fruiting trees, feed with Master Bloom fertilizer in the fall to winter-harden and improve next year's display. Remember to water before applying liquid fertilizers. If a tree has just been repotted, fertilize after it has had several weeks to adjust to its new soil.
These are mostly deciduous and evergreen trees and shrubs from cool temperate climates, which have a definite dormant season. The ideal location is on a bench or table at a good viewing height, on a patio, deck or balcony where the plant will have morning sun, afternoon shade, and shelter from drying winds. Avoid heat-reflective walls, and keep off the ground. Generally, outdoor bonsai can tolerate full sun most of the late fall, winter and early spring. Pines and junipers can take full sun year round, but will tend to yellow; for best color, shade them from hottest (midday to late afternoon) sun. Maples, azaleas, rhododendrons, and other plants with delicate foliage should be placed in 50-70% shade. Turn the tree monthly for even lighting & growth, more frequently in the spring. Outdoor bonsai may be displayed indoors 2-3 days per month at the most, but keep them away from direct sunlight, fireplaces, and heat sources.
In our area, mosts outdoor bonsai plants will not require frost protection, since many are dormant during the cold months. If you are concerned, you can bring your plants into a protected patio or into a garage or into an unheated greenhouse if temperatures are abnormally cold.
Indoor bonsai are largely evergreen tropical, sub-tropical and warm temperature climate plants(house plants) which normally experience little if any dormant period. Winter air temperatures should range from 50 degrees F night to 75 degrees F day for most sub-tropicals, 10 degrees F lower for cooler climate plants such as conifers. Summer temperatures can be higher. Humidity should be fairly high. Placement in the kitchen, bathroom or on a saucer with a layer of pebbles and water will help raise the humidity. Adequate light may be found at an east or west window in the fall, winter or spring. In these locations, summer light is best filtered through a sheer curtain.
Trimming, Pruning, Training
Remove vigorous new growth in the spring and periodically throughout the growing season. Never remove all the new growth at one time. Remove training wire (if any) after several months by snipping into short lengths. Do not allow wire to stay on the tree long enough to create scars. If the tree springs out of its wired shape, you can rewire it in the opposite direction, to avoid applying the wire in exactly the same place as before.
Deciduous trees should be re potted every 2-3 years. Slower growing evergreens need repotting every 4-5 years. Examine the root system in late fall to determine if the tree needs repotting. If repotting is required, plan to do it before the start of the next growing season. Always use a well-drained soil mix containing some sharp sand (1/8" - 1/16"); this makes the roots divide and keeps them vigorous.
Pests and Diseases
Although miniatures, bonsai can experience the same problems as their larger relatives, and should also be treated with the appropriate insecticides or fungicides. Because they are in containers, it is recommended to use an insect or fungus control that is also okay to use on house plants or vegetables. This will help prevent potential leaf damage.